Froth flotation of minerals



1 tion will be apparent No Drawing.

Patented Aug. 18, 1931 warren STATES PATENT oF1-"1c ROBERT L. PERKINS,OF EAST AURORA, NEW YORK, ASSIGNOR TO NATIONAL ANILINE & CHEMICALCOMPANY, INC.,

OF NEW YORK, N. Y., A CORPORATION OF NEW YORK rRoTH FLOTA'IION orMINER-Ans agents in the froth flotation of minerals and ores. Anotherobject of the invention is the preparation of new organic compoundswhich are esters of alkyl or aralkyl xanthic acids. These and otherobjects of the invenfrom a consideration of the following disclosurewhich is'given for the purpose of illustrating the invention.

Metal xanthates (metal salts of alkyl Xanthic acids) have been prepared,as is well known, by reacting an alcohol with carbon bisulfide and asuitable metal hydroxide, and it has been heretofore proposed to employsuch xanthates as modifying orcollectiing agents in the froth flotationof minera s.

It has beenfound that by the treatment of a suitable metal xanthate witha suitable aryl or aralkyl derivative, esters of alkyl and aralkylxanthic acids can be 'obtainedwhich contain an 'aryl nucleus in theircomposition and which correspond with the probable formula:

' ROCSSR' wherein R is an alkyl or aralkyl radical (such a 2 5-3 3 1 4 9a ing agents when einployed in the separation Application filed April22,

1929/ s m No. 357,338.

of minerals and concentration of ores by froth flotation; particularlywhen R in the above formula is a hydrocarbon radical which contains aposition, and especially when R isa hydrocarbon radical of the benzeneseries, specifically a phenyl radical.

n preparing the esters of the present invention' according. to apreferred method of procedure, an alkali-metal salt of an alkyl oraralkyl 'xanthic acid is reacted with a diazo salt of an aromaticcompound, or with a halide of an aryl-aliphatic compound, preferably ina suitable solvent or diluent; such as, water, alcohol, and the lik Thephenyl radical in its combodies thus obtained are the crude estersv ofthe present invention. They are generally oils substantially insolublein water and soluble in ether (and benzene. If desired, the crude esterscan be purified by a suitable treatment.

In utilizing the said esters in the froth flotation of minerals and theconcentration of ores, the mineral or ore is subjected to frothflotation in the presence of one or more of s'aidesters, which may beeither crude or purified, andwhich may be incorporated with the ore orthe mineral pulp in any suitable manner and at any suitable time thatwill produce satisfactory flotation. Thus,.they may beadded to theorewhile it is being reduced to a pulp, or they may be added to the pulpeither before or after its introduction into the flotation machine theymay, if necessary, be used in conjunction with a suitable or well knownfrothing agent, such as, pine may be employed in a neutral, alkaline oracid circuit; although a non-acid circuit is preferred; they may beemployed in admixture with each other or with other suitable flotationreagents, such as, the organic sul fides, polysulfides, other xanthates,etc.; and they may be added as such or in the form of a solution orsuspension in a suitable solventor suspension medium, such as, water, a

. dry ore will be suificient for satisfactory operation.

For a better understanding of the invention, reference should be had tothe following specific examples wherein are described and illustratedrepresentative products and methods for producing and employing saidproducts in accordance with the invention; but it is to be understoodthat the invention is not limited thereto. The parts are by weight.

.Aryl esters of xanthic acids E wample 1 Phenyl ester of methyl xanthicacids.9.3 parts of aniline is diazotized in the usual manner with sodiumnitrite and hydrochloric acid, and the solutions are treated with sodiumcarbonate solution until faintly acid to Congo red paper. 14.7 partsofpotassium methyl xanthate are dissolved in about 100 parts-of water atabout 80 C. The diazotized aniline solution is slowly run into the warmagitated xanthate srlution, nitrogen being given off in the reaction.Care is taken to prevent the reaction from foaming .over due to the toorapid evolution of nitrogen. Upon completion of the addition of thediazo solution, the reaction mixture is agitated for an additional hourand then allowed to stratify by standing for about an hour. The oilwhich separates is removed from the aqueous layer, isfiltered withsuction, is washed, first with dilute caustic alkali,

then with dilute acid, and then with water until the Wash water reactsneutral to Congo red paper, and is dried over anhydrous sodium sulfate.The phenyl ester of methyl xanthic acid thus obtained has the probableformula CH OCSSC H and is a dark red- C brown oil, very slightly solublein water, and

readily soluble in ether. If desired, the ester 7 can be furtherpurified by distillation with steam, extraction of the distillate withether, and evaporation of the ether from the extract;

E mample 2: Tolyl ester of isopropyl mamtkz'c acid.60 parts of isopropylalcohol, 40 parts of sodium hydroxide and 7 6 part-s of carbon bisulfideare mixed with agitation while maintaining the temperature between about20 to 28 C. 38 parts of the resulting crude sodium isopropyl xanthate isdissolved in about 300 parts of water, and the excess alkali isneutralized with hydrochloric acid until neutral to Clayton yellowpaper. 21.4 parts of o-toluidine are diazotized with sodium nitrite andhydrochloric acid in the usual manner, the solution is treated withsodium carbonate solution until faintly acid to Congo red paper, and theresulting o-diazo-toluene chloride solution is gradually added to theaqueous isopropyl xanthate solution heated to a temperature of about C.The temperature rises to about 90 to 95 C. Upon treating the resultingreaction mixture in the manner described in Example 1, the o-tolyl esterof isopropyl xanthic acid having the probable formula c11ocssc@u.crn OH:is obtained as a red-brown oil, soluble in ether and benzol, and veryslightly soluble in water.

If, in the above examples, there are substituted for the alkali-metalxanthates therein employed corresponding molecular proportions of othersuitable salts of alkyl or aralkyl xanthic acids (e. g., sodium methylxanthate, alkali-metal salts of normal propyl xanthic acid, of normaland iso-butyl xanthic acids, of normal and iso-amyl xanthic acids, ofnormal hexyl xanthic acid, of normal heptyl xanthic acid, of normaloctyl xanthic acid, of normal nonyl xanthic acid, of benzyl xanthicacid, of phenyl ethyl xanthic acid, of cyclo-hexyl xanthic acid, etc.)and/or there are substituted for the salts of diazotized aniline ando-toluidine therein employed corresponding molecular proportions ofother salts of diazotized aryl amines (e. g., the chlorides or sulfatesof diazotized p-toluidine, of diazotized xylidine, of diazoti-zedcumidine. of diazotized benzidine, of diazotized anisidines, ofdiazotized alphaor beta-naphthylamines, of diazotized betaaminoanthraquinone, and the like) corresponding aryl esters of alkyl oraralkyl xanthic acids may be obtained. These esters are all included inthe probable, general formula ROCSSR wherein R is CH C H ,C H,, C5H11, e1s C7H15'", s i7' C9H19 7 H or an aralkyl radical; and R. is an arylradical.

Instead of a diazotized arylamine, an aralkyl halide (e. g., benzylchloride or bromide, phenyl ethyl chloride or bromide, triphenyl methylchloride or bromide. etc.) may be reacted with a metal salt of an alkyl.or aralkyl xanthic acid, as illustrated in the following example,whereby aralkyl esters of alkyl or aralkyl xanthic acids may be obtainedhaving the probable, general formula:

ROCSSR Ara-llc yl esters of wanthz'c acids Example 3: Benzy l ester ofethyl xanthic acid.12.6 parts of benzyl chloride are mixed with 16.1parts of potassium ethyl xanthate and 80 parts of ethyl alcohol(denatured), and the mixture is continuously agitated at roomtemperature for'several hours. The resulting mixture is added to about1,000 parts of water, the water layer is drawn off. and the oil is againwashed with about 500 parts of water. The mixture is filtered and thefiltrate is allowed to stratify. The oily layer is separated from theaqueous layer, dried over anhydrous sodium sulfate, then over of phenylester of ethyl calcium chloride, and thenvacuum distilled. The benzylester of ethyl xanthic acid thus obtained is apractically colorlessliquid having a faint odor. It does not solidify at 0 (3., boils at atemperature of about 17 25 1]. (corn) under 15 millimeters pressure, issoluble in alcohol to the extent of about 1 part in 6 parts of alcoholat 21 (3., is very slightly soluble in water, and readily soluble inether and benzol. It has the probable formula, C H OCSSCH C H Flotation'of minerals Example 4-500 parts of a copper sulfide ore (from the Chinomine of the Nevada Consolidated Copper Co., Hurley, N. M.) assaying 1.26per cent copper, were ground in a ball mill with 215 parts of water andabout 0.7 parts hydrated lime (equivalent to about 3 pounds hydratedlime perton of dry ore) until practically all of the mixture wassulficiently fine to pass a 40 mesh screen (about 1 hour). The groundpulp was diluted with sufficient Water to give a mixture containingabout 16 per cent solids, and about 0.054 parts xanthic acid,

. c mocssdm,

(equivalent to about one-fifth pound per ton of dry ore) was added. Themixture was subjected to agitation in a J anney flotation apparatus fora few minutes, then a small amount, e. g., 0.02 to 0.03 parts, ofpineoil Was added, and agitation and flotation were carried out for about 15minutes with addition of about 0.02 to 0.03 more parts of pine oil. Therougher concentrate thus obtained was refioated for about 5 minuteswithout any additional flotation agent but with the addition of anothersmall amount of pine oil. 27.5 parts of a cleaner concentrate assaying19.18 per cent copper were obtained. A re-' covery of about 84 per centofthe copper was therefore obtained in the cleaner concentrate. Thetailings assayed "0.145 per cent copper. The equivalent of about 18.3tons of ore was required to give about 1 ton of concentrate.

Example 5,-500 parts of copper sulfide ore (from the Chino mine of theNevada Consolidated Copper Go.) assaying 1.33 per cent formula whereinR- is CHF,

copper were treated as described in Examdrated lime (equivalent to about4 pounds per ton of dry ore) and about 0.05 part of phenyl ester ofmethyl xanthic acid, oH.0osso.H., produced as escribed in Example 1,(equivalent to about 0.2 pounds per ton of dry ore) were employed. 10.6parts of a' concentrate assaying 42.90 per cent copper were obtained.The tailings assayed 0.25 per cent copper. This illustrates the highselective action of the esters of the present invention with respecttocopper sulfide minerals.

In a similar manner other aryl and aralkyl esters of alkyl and aralkylxanthic acids may be employed as collecting agents in the frothflotation of minerals and the concentration of'ores. i

It will be understood that the invention is not limited to the specificexamples given above, butmay be varied within wide limits metalxanthates may be employed, and even i the crude reaction mixtureresulting from the reaction of an alcohol, carbon disulfide and analkali-metal hydroxide may often be used. The diazo-aromatic saltsemployed may be prepared in any suitable manner, preferably by thediazotization of the corresponding primary aromatic amine. I

I claim:

1. A composition of matter comprising an ester of a xanthic acid havingthe probable formula 1 ROCSSR' wherein R is 'CH C H 5 11 O6H13, 07H C9H9 06H R'is an aryl C4H9 7 15 s 17 or an aralkyl radical; and or aralkylradical.

. 0 X A compos1t1on of matter COIIIPIlSll'lg an ester of a xanthic acidhaving the probable ROCSSR 3 71 C4H9 C5H11 c 1s 7 15 a 11 9 C H or anaralkyl radical; and R is a hydrocarbon radical which contains a phenylradical in its composition.

3. A composition of matter comprising an ester of a xanthic acid havingthe probable C H C H and R is. anaryl or aralkyl radical.

ester of a xanthic acid having the probable formula ROCSSR wherein R isCH C I-I C H C5H117 e 13 i 15 s 17 C H C H or an aralkylradical; and Ris an aryl radical.

5. A composition of matter comprising an ester of a xanthic acid havingthe probable formula ROCSSR" C H C H or an aralkyl radical; and

R" is a hydrocarbon radical of the benzene serles.

6. A composltion of matter comprising an ester of a xanthic acid havingthe probable formula C9I-I C H or an aralkyl radical; and R" is a phenylradical.

7 A composition of matter comprising an ester of an alkyl Xanthic acidhaving the probable formula ROCSSR" 8. A composition of mattercomprising an ester of an alkyl xanthic acid having the probable formulaC I-I or C H and R is a hydrocarbon radical of the benzene series.

9. A composition of matter comprising an ester of an alkyl xanthic acidhaving the probable formula C H or C I-I and R" is a phenyl radical.

10. A composition of matter comprising an ester of an alkyl xanthic acidhaving the probable formula nocss'ofins 11. In the separation ofminerals by flotation, the step which comprises subjecting a mineralpulp to a froth flotation operation in the presence of an ester of axanthic acid having the probable formula ROOSSR wherein R is an alkyl oraralkyl radical, and R is an aryl or aralkyl radical.

12. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp to a froth flotation operation in the presenceof an ester of a xanthic acid having the probable formula ROCSSR' ROCSSRwherein R is an alkyl or aralkyl radical, and R is a hydrocarbon radicalwhich contains a phenyl radical in its composition.

14. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp to a froth flotation operation in the presenceof an ester of a Xanthic acid havingthe probable formula ROCSSR whereinR is an alkyl or aralkyl group and R" is an aryl radical.

15. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp to a froth flotation operation in the presenceofv an ester of'a xanthic acid having the probable'formula ROCSSRwherein R is an alkyl or aralkyl group and R is a phenyl radical.

16. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp. to a froth flotation operation in the.presence'of an ester of an alkyl xanthic acid having the probableformula ROCSSR' wherein R is an alkyl group and R is an aryl or aralkylradical.

17. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp to a froth flotation operation in the presenceof an ester of an alkyl xanthic acid having the probable formula ROCSSRwherein R is an alkyl group and R is a hydrocarbon radical whichcontains a phenyl radical in its composition.

18. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp to a froth flotation operation in the presenceof an ester of an alkyl xanthic acid having the probable formula nocssa"wherein R is analkyl group and R" is a phenyl radical. y

19. In the separation of minerals by flotation, the step which comprisessubjecting a mineral pulp to a froth flotation operatlon in the presenceof an ester of an alkyl xanthic acid having the probable formulaROGSSCBI-L wherein R is an alkyl group. a

20. In the separation of minerals by flotation, the step which comprisessubjecting a copper sulfide mineral pulp to a froth. flotation operationin'- the presence of an ester of a xanthic" acid having the probableformula ROCSSR' wherein R is an alkyl or aralkyl radical,

and R is an aryl or aralkyl radical.

21. In the separation of minerals by flotation, the step which comprisessubjecting a copper sulfide mineral pu p to a froth flotation operationin the presence of an ester of a xanthic acid having the probableformula ROCSSR" wherein R isan alkyl or aralkyl group and R is a phenylradical.

22. In the separation of minerals by flotation, the step which comprisessubjecting a copper sulfide mineral pulp to a froth flotation operationin the presence of an ester of an alkyl formula xanthic acid having theprobable ROCSSR' wherein R is an alkyl group and R is a aryl or aralkylradical.

23. In the separation of minerals by flotation, the step which comprisessubjecting a copper sulfide mineral pulp to a froth flotation operationin the presence of an ester of an alkyl xanthic acid having the probableformula aocss can,

wherein R is an alkyl group. p

In testimony whereof I aflix my signature.

ROBERT L. PERKIN

